The goal of this research is to quantify and to assess the reliability of the two scintigraphic measures of coronary artery disease. The two techniques are ECG grated radionuclide angiography and thallium scintigraphy obtained during rest and exercise conditions. The analysis procedures will be designed to limit differences due to visual interpretation and the quantitative results will provide a more sensitive means of categorizing coronary artery disease. The rationale for analysis of planar thallium scintigrams will entail development of a model to quantitate thallium distribution in scintigrams previously obtained in an experimental dog infarct model. Histologic measures of infarct size and location are available from thallium autoradiography and nitrobluetetrazolium staining of 20 micron tissue sections. Following development, the planar thallium model will be applied to rest and exercise scintigrams obtained in the clinical situation. Additional clinical scintigraphic data will include thallium tomograms obtained with a random pinhole aperture, and ECG gated radionuclide ventriculograms obtained during rest and exercise conditions. Global and local left ventricular function will be evaluated from radionuclide angiograms by analysis of radioactivity changes from diastole to systole in the total and segmental left ventricular areas respectively. All scintigraphic data will be compared to results of contrast cineangiography including sites or coronary stenosis and cardiac function measured by ejection fraction and regional heart wall motion. The sensivity and specificity of the scintigraphic techniques for the detection of coronary artery disease will be evaluated.